1. Field of the Invention
The present invention generally relates to duplex communications and, more particularly, to echo cancellation.
2. Background of the Invention
During a duplex communication session, for instance between two telephones, acoustic echo arises when output audio signals generated by a first device's loudspeaker are detected by the device's microphone. If not addressed, the acoustic echo will be communicated back to a second device that was the original source of the audio signal, which is undesirable.
Echo cancellers using linear and non-linear processing techniques oftentimes are used to reduce acoustic echo. Such echo cancellers typically include a double talk (DBTK) detector. A DBTK detector typically generates a DBTK flag to indicate whether there are is an audio signal on a communication device's downlink signal path, on the communication device's uplink signal path, or both on the downlink and uplink signal paths. When the DBTK flag indicates that an audio signal is present on the downlink signal path or both on the downlink and uplink signal paths, the echo canceller generally will implement some form of echo cancellation.
Unfortunately, in addition to echo, other noise may be present in communication signals, for instance background noise when a communication device is used in a noisy environment. Such noise can disrupt operation of an echo canceller. Indeed, noise oftentimes causes improper DBTK detection, which can result in improper echo cancellation, as well as introduce other signal processing errors.